TLine.cxx

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// @(#)root/graf:$Id$
// Author: Rene Brun   12/12/94
 
/*************************************************************************
 * Copyright (C) 1995-2000, Rene Brun and Fons Rademakers.               *
 * All rights reserved.                                                  *
 *                                                                       *
 * For the licensing terms see $ROOTSYS/LICENSE.                         *
 * For the list of contributors see $ROOTSYS/README/CREDITS.             *
 *************************************************************************/
 
#include <stdlib.h>
 
#include <iostream>
#include "TROOT.h"
#include "TBuffer.h"
#include "TLine.h"
#include "TVirtualPad.h"
#include "TClass.h"
#include "TVirtualX.h"
#include "TMath.h"
#include "TPoint.h"
 
ClassImp(TLine);
 
/** \class TLine
\ingroup BasicGraphics
 
Use the TLine constructor to create a simple line.
 
~~~ {.cpp}
   TLine(Double_t x1,Double_t y1,Double_t x2,Double_t y2)
~~~
 
`x1`, `y1`, `x2`, `y2` are the coordinates of the first and the second point.
 
_**Example**_:
 
~~~ {.cpp}
   root[] l = new TLine(0.2,0.2,0.8,0.3)
   root[] l->Draw()
~~~
*/
 
 
////////////////////////////////////////////////////////////////////////////////
/// Line normal constructor.
 
TLine::TLine(Double_t x1, Double_t y1, Double_t x2, Double_t  y2)
      :TObject(), TAttLine()
{
   fX1=x1; fY1=y1; fX2=x2; fY2=y2;
}
 
 
////////////////////////////////////////////////////////////////////////////////
/// Line copy constructor.
 
TLine::TLine(const TLine &line) : TObject(line), TAttLine(line), TAttBBox2D(line)
{
   line.TLine::Copy(*this);
}
 
////////////////////////////////////////////////////////////////////////////////
/// Assignment operator
 
TLine &TLine::operator=(const TLine &src)
{
   src.TLine::Copy(*this);
   return *this;
}
 
////////////////////////////////////////////////////////////////////////////////
/// Copy this line to line.
 
void TLine::Copy(TObject &obj) const
{
   TObject::Copy(obj);
   TAttLine::Copy(((TLine&)obj));
   ((TLine&)obj).fX1 = fX1;
   ((TLine&)obj).fY1 = fY1;
   ((TLine&)obj).fX2 = fX2;
   ((TLine&)obj).fY2 = fY2;
}
 
////////////////////////////////////////////////////////////////////////////////
/// Compute distance from point px,py to a line.
 
Int_t TLine::DistancetoPrimitive(Int_t px, Int_t py)
{
   if (!TestBit(kLineNDC)) return DistancetoLine(px,py,gPad->XtoPad(fX1),gPad->YtoPad(fY1),gPad->XtoPad(fX2),gPad->YtoPad(fY2));
   Double_t x1 = gPad->GetX1() + fX1*(gPad->GetX2()-gPad->GetX1());
   Double_t y1 = gPad->GetY1() + fY1*(gPad->GetY2()-gPad->GetY1());
   Double_t x2 = gPad->GetX1() + fX2*(gPad->GetX2()-gPad->GetX1());
   Double_t y2 = gPad->GetY1() + fY2*(gPad->GetY2()-gPad->GetY1());
   return DistancetoLine(px,py,x1,y1,x2,y2);
}
 
////////////////////////////////////////////////////////////////////////////////
/// Draw this line with new coordinates.
 
TLine *TLine::DrawLine(Double_t x1, Double_t y1, Double_t x2, Double_t  y2)
{
   TLine *newline = new TLine(x1, y1, x2, y2);
   TAttLine::Copy(*newline);
   newline->SetBit(kCanDelete);
   newline->AppendPad();
   return newline;
}
 
////////////////////////////////////////////////////////////////////////////////
/// Draw this line with new coordinates in NDC.
 
TLine *TLine::DrawLineNDC(Double_t x1, Double_t y1, Double_t x2, Double_t  y2)
{
   TLine *newline = DrawLine(x1, y1, x2, y2);
   newline->SetBit(kLineNDC);
   return newline;
}
 
////////////////////////////////////////////////////////////////////////////////
/// Execute action corresponding to one event.
///  This member function is called when a line is clicked with the locator
///
///  If Left button clicked on one of the line end points, this point
///     follows the cursor until button is released.
///
///  if Middle button clicked, the line is moved parallel to itself
///     until the button is released.
 
void TLine::ExecuteEvent(Int_t event, Int_t px, Int_t py)
{
   if (!gPad) return;
 
   Int_t kMaxDiff = 20;
   static Int_t d1,d2,px1,px2,py1,py2;
   static Int_t pxold, pyold, px1old, py1old, px2old, py2old;
   static Double_t oldX1, oldY1, oldX2, oldY2;
   static Bool_t p1, p2, pL, ndcsav;
   Double_t dpx,dpy,xp1,yp1;
   Int_t dx, dy;
 
   Bool_t opaque  = gPad->OpaqueMoving();
 
   if (!gPad->IsEditable()) return;
 
   switch (event) {
 
   case kArrowKeyPress:
   case kButton1Down:
      oldX1 = GetX1();
      oldY1 = GetY1();
      oldX2 = GetX2();
      oldY2 = GetY2();
      ndcsav = TestBit(kLineNDC);
      if (!opaque) {
         gVirtualX->SetLineColor(-1);
         TAttLine::Modify();  //Change line attributes only if necessary
      }
 
      // No break !!!
 
   case kMouseMotion:
 
      if (TestBit(kLineNDC)) {
         px1 = gPad->UtoPixel(GetX1());
         py1 = gPad->VtoPixel(GetY1());
         px2 = gPad->UtoPixel(GetX2());
         py2 = gPad->VtoPixel(GetY2());
      } else {
         px1 = gPad->XtoAbsPixel(gPad->XtoPad(GetX1()));
         py1 = gPad->YtoAbsPixel(gPad->YtoPad(GetY1()));
         px2 = gPad->XtoAbsPixel(gPad->XtoPad(GetX2()));
         py2 = gPad->YtoAbsPixel(gPad->YtoPad(GetY2()));
      }
      p1 = p2 = pL = kFALSE;
 
      d1  = abs(px1 - px) + abs(py1-py); //simply take sum of pixels differences
      if (d1 < kMaxDiff) { //*-*================>OK take point number 1
         px1old = px1; py1old = py1;
         p1 = kTRUE;
         gPad->SetCursor(kPointer);
         return;
      }
      d2  = abs(px2 - px) + abs(py2-py); //simply take sum of pixels differences
      if (d2 < kMaxDiff) { //*-*================>OK take point number 2
         px2old = px2; py2old = py2;
         p2 = kTRUE;
         gPad->SetCursor(kPointer);
         return;
      }
 
      pL = kTRUE;
      pxold = px; pyold = py;
      gPad->SetCursor(kMove);
 
      break;
 
   case kArrowKeyRelease:
   case kButton1Motion:
 
      if (p1) {
         if (!opaque) {
            gVirtualX->DrawLine(px1old, py1old, px2, py2);
            gVirtualX->DrawLine(px, py, px2, py2);
         } else {
            if (ndcsav) {
               SetNDC(kFALSE);
               SetX2(gPad->GetX1() + oldX2*(gPad->GetX2()-gPad->GetX1()));
               SetY2(gPad->GetY1() + oldY2*(gPad->GetY2()-gPad->GetY1()));
            }
            SetX1(gPad->AbsPixeltoX(px));
            SetY1(gPad->AbsPixeltoY(py));
         }
         px1old = px;
         py1old = py;
      }
      if (p2) {
         if (!opaque) {
            gVirtualX->DrawLine(px1, py1, px2old, py2old);
            gVirtualX->DrawLine(px1, py1, px, py);
         } else {
            if (ndcsav) {
               SetNDC(kFALSE);
               SetX1(gPad->GetX1() + oldX1*(gPad->GetX2()-gPad->GetX1()));
               SetY1(gPad->GetY1() + oldY1*(gPad->GetY2()-gPad->GetY1()));
            }
            SetX2(gPad->AbsPixeltoX(px));
            SetY2(gPad->AbsPixeltoY(py));
         }
         px2old = px;
         py2old = py;
      }
      if (pL) {
         if (!opaque) gVirtualX->DrawLine(px1, py1, px2, py2);
         dx = px-pxold;  dy = py-pyold;
         px1 += dx; py1 += dy; px2 += dx; py2 += dy;
         if (!opaque) gVirtualX->DrawLine(px1, py1, px2, py2);
         pxold = px;
         pyold = py;
         if (opaque) {
            if (ndcsav) SetNDC(kFALSE);
            SetX1(gPad->AbsPixeltoX(px1));
            SetY1(gPad->AbsPixeltoY(py1));
            SetX2(gPad->AbsPixeltoX(px2));
            SetY2(gPad->AbsPixeltoY(py2));
         }
      }
      if (opaque) {
         if (p1) {
            //check in which corner the BBox is edited
            if (GetX1() > GetX2()) {
               if (GetY1() > GetY2())
                  gPad->ShowGuidelines(this, event, '2', true);
               else
                  gPad->ShowGuidelines(this, event, '3', true);
            } else {
               if (GetY1() > GetY2())
                  gPad->ShowGuidelines(this, event, '1', true);
               else
                  gPad->ShowGuidelines(this, event, '4', true);
            }
         }
         if (p2) {
            //check in which corner the BBox is edited
            if (GetX1() > GetX2()) {
               if (GetY1() > GetY2())
                  gPad->ShowGuidelines(this, event, '4', true);
               else
                  gPad->ShowGuidelines(this, event, '1', true);
            } else {
               if (GetY1() > GetY2())
                  gPad->ShowGuidelines(this, event, '3', true);
               else
                  gPad->ShowGuidelines(this, event, '2', true);
            }
         }
         if (pL) {
            gPad->ShowGuidelines(this, event, 'i', true);
         }
         gPad->Modified(kTRUE);
         gPad->Update();
      }
      break;
 
   case kButton1Up:
 
      if (gROOT->IsEscaped()) {
         gROOT->SetEscape(kFALSE);
         if (opaque) {
            SetX1(oldX1);
            SetY1(oldY1);
            SetX2(oldX2);
            SetY2(oldY2);
            gPad->Modified(kTRUE);
            gPad->Update();
         }
         break;
      }
      if (opaque) {
         if (ndcsav && !TestBit(kLineNDC)) {
            SetX1((GetX1() - gPad->GetX1())/(gPad->GetX2()-gPad->GetX1()));
            SetX2((GetX2() - gPad->GetX1())/(gPad->GetX2()-gPad->GetX1()));
            SetY1((GetY1() - gPad->GetY1())/(gPad->GetY2()-gPad->GetY1()));
            SetY2((GetY2() - gPad->GetY1())/(gPad->GetY2()-gPad->GetY1()));
            SetNDC();
         }
         gPad->ShowGuidelines(this, event);
      } else {
         if (TestBit(kLineNDC)) {
            dpx  = gPad->GetX2() - gPad->GetX1();
            dpy  = gPad->GetY2() - gPad->GetY1();
            xp1  = gPad->GetX1();
            yp1  = gPad->GetY1();
            if (p1) {
               SetX1((gPad->AbsPixeltoX(px)-xp1)/dpx);
               SetY1((gPad->AbsPixeltoY(py)-yp1)/dpy);
            }
            if (p2) {
               SetX2((gPad->AbsPixeltoX(px)-xp1)/dpx);
               SetY2((gPad->AbsPixeltoY(py)-yp1)/dpy);
            }
            if (pL) {
               SetX1((gPad->AbsPixeltoX(px1)-xp1)/dpx);
               SetY1((gPad->AbsPixeltoY(py1)-yp1)/dpy);
               SetX2((gPad->AbsPixeltoX(px2)-xp1)/dpx);
               SetY2((gPad->AbsPixeltoY(py2)-yp1)/dpy);
            }
         } else {
            if (p1) {
               SetX1(gPad->PadtoX(gPad->AbsPixeltoX(px)));
               SetY1(gPad->PadtoY(gPad->AbsPixeltoY(py)));
            }
            if (p2) {
               SetX2(gPad->PadtoX(gPad->AbsPixeltoX(px)));
               SetY2(gPad->PadtoY(gPad->AbsPixeltoY(py)));
            }
            if (pL) {
               SetX1(gPad->PadtoX(gPad->AbsPixeltoX(px1)));
               SetY1(gPad->PadtoY(gPad->AbsPixeltoY(py1)));
               SetX2(gPad->PadtoX(gPad->AbsPixeltoX(px2)));
               SetY2(gPad->PadtoY(gPad->AbsPixeltoY(py2)));
            }
         }
         if (TestBit(kVertical)) {
            if (p1) SetX2(GetX1());
            if (p2) SetX1(GetX2());
         }
         if (TestBit(kHorizontal)) {
            if (p1) SetY2(GetY1());
            if (p2) SetY1(GetY2());
         }
         gPad->Modified(kTRUE);
         gPad->Update();
         if (!opaque) gVirtualX->SetLineColor(-1);
      }
      break;
 
   case kButton1Locate:
 
      ExecuteEvent(kButton1Down, px, py);
      while (1) {
         px = py = 0;
         event = gVirtualX->RequestLocator(1,1,px,py);
 
         ExecuteEvent(kButton1Motion, px, py);
 
         if (event != -1) {                     // button is released
            ExecuteEvent(kButton1Up, px, py);
            return;
         }
      }
   }
}
 
////////////////////////////////////////////////////////////////////////////////
/// List this line with its attributes.
 
void TLine::ls(Option_t *) const
{
   TROOT::IndentLevel();
   printf("%s  X1=%f Y1=%f X2=%f Y2=%f\n",IsA()->GetName(),fX1,fY1,fX2,fY2);
}
 
////////////////////////////////////////////////////////////////////////////////
/// Paint this line with its current attributes.
 
void TLine::Paint(Option_t *)
{
   if (TestBit(kLineNDC)) PaintLineNDC(fX1,fY1,fX2,fY2);
   else                   PaintLine(gPad->XtoPad(fX1),gPad->YtoPad(fY1),gPad->XtoPad(fX2),gPad->YtoPad(fY2));
}
 
////////////////////////////////////////////////////////////////////////////////
/// Draw this line with new coordinates.
 
void TLine::PaintLine(Double_t x1, Double_t y1, Double_t x2, Double_t y2)
{
   TAttLine::Modify();  //Change line attributes only if necessary
   gPad->PaintLine(x1,y1,x2,y2);
}
 
////////////////////////////////////////////////////////////////////////////////
/// Draw this line with new coordinates in NDC.
 
void TLine::PaintLineNDC(Double_t u1, Double_t v1, Double_t u2, Double_t v2)
{
   TAttLine::Modify();  //Change line attributes only if necessary
   gPad->PaintLineNDC(u1,v1,u2,v2);
}
 
////////////////////////////////////////////////////////////////////////////////
/// Dump this line with its attributes.
 
void TLine::Print(Option_t *) const
{
   printf("%s  X1=%f Y1=%f X2=%f Y2=%f",IsA()->GetName(),fX1,fY1,fX2,fY2);
   if (GetLineColor() != 1) printf(" Color=%d",GetLineColor());
   if (GetLineStyle() != 1) printf(" Style=%d",GetLineStyle());
   if (GetLineWidth() != 1) printf(" Width=%d",GetLineWidth());
   printf("\n");
}
 
////////////////////////////////////////////////////////////////////////////////
/// Save primitive as a C++ statement(s) on output stream out
 
void TLine::SavePrimitive(std::ostream &out, Option_t * /*= ""*/)
{
   if (gROOT->ClassSaved(TLine::Class())) {
      out<<"   ";
   } else {
      out<<"   TLine *";
   }
   out<<"line = new TLine("<<fX1<<","<<fY1<<","<<fX2<<","<<fY2<<");"<<std::endl;
 
   SaveLineAttributes(out,"line",1,1,1);
 
   if (TestBit(kLineNDC))
      out<<"   line->SetNDC();"<<std::endl;
 
   out<<"   line->Draw();"<<std::endl;
}
 
////////////////////////////////////////////////////////////////////////////////
/// Check whether this line is to be drawn horizontally.
 
Bool_t TLine::IsHorizontal()
{
   return TestBit(kHorizontal);
}
 
////////////////////////////////////////////////////////////////////////////////
/// Check whether this line is to be drawn vertically.
 
Bool_t TLine::IsVertical()
{
   return TestBit(kVertical);
}
 
////////////////////////////////////////////////////////////////////////////////
/// Set NDC mode on if isNDC = kTRUE, off otherwise
 
void TLine::SetNDC(Bool_t isNDC)
{
   ResetBit(kLineNDC);
   if (isNDC) SetBit(kLineNDC);
}
 
////////////////////////////////////////////////////////////////////////////////
/// Force the line to be drawn horizontally.
/// Makes fY2 equal to fY1. The line length is kept.
/// TArrow and TGaxis also get this function by inheritance.
 
void TLine::SetHorizontal(Bool_t set /*= kTRUE*/)
{
   SetBit(kHorizontal, set);
   if (set) {
      SetVertical(kFALSE);
      Int_t px1 = gPad->XtoAbsPixel(fX1);
      Int_t px2 = gPad->XtoAbsPixel(fX2);
      Int_t py1 = gPad->YtoAbsPixel(fY1);
      Int_t py2 = gPad->YtoAbsPixel(fY2);
      Int_t l   = Int_t(TMath::Sqrt((px2-px1)*(px2-px1)+(py2-py1)*(py2-py1)));
      if (fX2 >= fX1) fX2 = gPad->AbsPixeltoX(px1+l);
      else            fX2 = gPad->AbsPixeltoX(px1-l);
      fY2 = fY1;
   }
}
 
////////////////////////////////////////////////////////////////////////////////
/// Force the line to be drawn vertically.
/// Makes fX2 equal to fX1. The line length is kept.
/// TArrow and TGaxis also get this function by inheritance.
 
void TLine::SetVertical(Bool_t set /*= kTRUE*/)
{
   SetBit(kVertical, set);
   if (set) {
      SetHorizontal(kFALSE);
      Int_t px1 = gPad->XtoAbsPixel(fX1);
      Int_t px2 = gPad->XtoAbsPixel(fX2);
      Int_t py1 = gPad->YtoAbsPixel(fY1);
      Int_t py2 = gPad->YtoAbsPixel(fY2);
      Int_t l   = Int_t(TMath::Sqrt((px2-px1)*(px2-px1)+(py2-py1)*(py2-py1)));
      if (fY2 >= fY1) fY2 = gPad->AbsPixeltoY(py1-l);
      else            fY2 = gPad->AbsPixeltoY(py1+l);
      fX2 = fX1;
   }
}
 
////////////////////////////////////////////////////////////////////////////////
/// Stream an object of class TLine.
 
void TLine::Streamer(TBuffer &R__b)
{
   if (R__b.IsReading()) {
      UInt_t R__s, R__c;
      Version_t R__v = R__b.ReadVersion(&R__s, &R__c);
      if (R__v > 1) {
         R__b.ReadClassBuffer(TLine::Class(), this, R__v, R__s, R__c);
         return;
      }
      //====process old versions before automatic schema evolution
      TObject::Streamer(R__b);
      TAttLine::Streamer(R__b);
      Float_t x1,y1,x2,y2;
      R__b >> x1; fX1 = x1;
      R__b >> y1; fY1 = y1;
      R__b >> x2; fX2 = x2;
      R__b >> y2; fY2 = y2;
      //====end of old versions
 
   } else {
      R__b.WriteClassBuffer(TLine::Class(),this);
   }
}
////////////////////////////////////////////////////////////////////////////////
/// Return the bounding Box of the Line
 
Rectangle_t TLine::GetBBox()
{
   Rectangle_t BBox;
   Int_t px1, py1, px2, py2;
   px1 = gPad->XtoPixel(fX1);
   px2 = gPad->XtoPixel(fX2);
   py1 = gPad->YtoPixel(fY1);
   py2 = gPad->YtoPixel(fY2);
 
   Int_t tmp;
   if (px1>px2) { tmp = px1; px1 = px2; px2 = tmp;}
   if (py1>py2) { tmp = py1; py1 = py2; py2 = tmp;}
 
   BBox.fX = px1;
   BBox.fY = py1;
   BBox.fWidth = px2-px1;
   BBox.fHeight = py2-py1;
 
   return (BBox);
}
 
////////////////////////////////////////////////////////////////////////////////
/// Return the center of the BoundingBox as TPoint in pixels
 
TPoint TLine::GetBBoxCenter()
{
   TPoint p;
   p.SetX(gPad->XtoPixel(TMath::Min(fX1,fX2)+0.5*(TMath::Max(fX1, fX2)-TMath::Min(fX1, fX2))));
   p.SetY(gPad->YtoPixel(TMath::Min(fY1,fY2)+0.5*(TMath::Max(fY1, fY2)-TMath::Min(fY1, fY2))));
   return(p);
}
 
////////////////////////////////////////////////////////////////////////////////
/// Set center of the BoundingBox
 
void TLine::SetBBoxCenter(const TPoint &p)
{
   Double_t w = TMath::Max(fX1, fX2)-TMath::Min(fX1, fX2);
   Double_t h = TMath::Max(fY1, fY2)-TMath::Min(fY1, fY2);
   if (fX2>fX1) {
      this->SetX1(gPad->PixeltoX(p.GetX())-0.5*w);
      this->SetX2(gPad->PixeltoX(p.GetX())+0.5*w);
   }
   else {
      this->SetX2(gPad->PixeltoX(p.GetX())-0.5*w);
      this->SetX1(gPad->PixeltoX(p.GetX())+0.5*w);
   }
   if (fY2>fY1) {
      this->SetY1(gPad->PixeltoY(p.GetY()-gPad->VtoPixel(0))-0.5*h);
      this->SetY2(gPad->PixeltoY(p.GetY()-gPad->VtoPixel(0))+0.5*h);
   }
   else {
      this->SetY2(gPad->PixeltoY(p.GetY()-gPad->VtoPixel(0))-0.5*h);
      this->SetY1(gPad->PixeltoY(p.GetY()-gPad->VtoPixel(0))+0.5*h);
   }
}
 
////////////////////////////////////////////////////////////////////////////////
/// Set X coordinate of the center of the BoundingBox
 
void TLine::SetBBoxCenterX(const Int_t x)
{
   Double_t w = TMath::Max(fX1, fX2)-TMath::Min(fX1, fX2);
   if (fX2>fX1) {
      this->SetX1(gPad->PixeltoX(x)-0.5*w);
      this->SetX2(gPad->PixeltoX(x)+0.5*w);
   }
   else {
      this->SetX2(gPad->PixeltoX(x)-0.5*w);
      this->SetX1(gPad->PixeltoX(x)+0.5*w);
   }
}
 
////////////////////////////////////////////////////////////////////////////////
/// Set Y coordinate of the center of the BoundingBox
 
void TLine::SetBBoxCenterY(const Int_t y)
{
   Double_t h = TMath::Max(fY1, fY2)-TMath::Min(fY1, fY2);
   if (fY2>fY1) {
      this->SetY1(gPad->PixeltoY(y-gPad->VtoPixel(0))-0.5*h);
      this->SetY2(gPad->PixeltoY(y-gPad->VtoPixel(0))+0.5*h);
   }
   else {
      this->SetY2(gPad->PixeltoY(y-gPad->VtoPixel(0))-0.5*h);
      this->SetY1(gPad->PixeltoY(y-gPad->VtoPixel(0))+0.5*h);
   }
}
 
////////////////////////////////////////////////////////////////////////////////
/// Set left hand side of BoundingBox to a value
/// (resize in x direction on left)
 
void TLine::SetBBoxX1(const Int_t x)
{
   if (fX2>fX1)
      this->SetX1(gPad->PixeltoX(x));
   else
      this->SetX2(gPad->PixeltoX(x));
}
 
////////////////////////////////////////////////////////////////////////////////
/// Set right hand side of BoundingBox to a value
/// (resize in x direction on right)
 
void TLine::SetBBoxX2(const Int_t x)
{
   if (fX2>fX1)
      this->SetX2(gPad->PixeltoX(x));
   else
      this->SetX1(gPad->PixeltoX(x));
}
 
////////////////////////////////////////////////////////////////////////////////
/// Set top of BoundingBox to a value (resize in y direction on top)
 
void TLine::SetBBoxY1(const Int_t y)
{
   if (fY2>fY1)
      this->SetY2(gPad->PixeltoY(y - gPad->VtoPixel(0)));
   else
      this->SetY1(gPad->PixeltoY(y - gPad->VtoPixel(0)));
}
 
////////////////////////////////////////////////////////////////////////////////
/// Set bottom of BoundingBox to a value
/// (resize in y direction on bottom)
 
void TLine::SetBBoxY2(const Int_t y)
{
   if (fY2>fY1)
      this->SetY1(gPad->PixeltoY(y - gPad->VtoPixel(0)));
   else
      this->SetY2(gPad->PixeltoY(y - gPad->VtoPixel(0)));
}